The amazing thing about this film is its actuality - it's a true story, general Schottland was actually a British spy in Germany from 1914 to the end of the second world war, with high responsibilities as a general and trusted implicitly by Hitler himself. The one fellow officer who didn't trust him is played by Alexander Knox who makes a fearful Nazi bully and idiot. Gia Scala plays the woman, a singer in a relationship with Jack Hawkins and others, and there is a traumatic story very similar to "The Counterfeit Traitor" with William Holden and Lilli Palmer some years later, but this is in black and white and sticks very strictly to realism, postponing true romance till after the war, if possible. The situation of general Schottland is hair-raising. His responsibility was tremendous, and he had the power and means to obstruct several of the most vital operations of the Germans during the war, for example the outcome of the battle of the Ardennes, actually causing immense casualties, and that's the shocking insight of this film - you learn how little millions of human lives mattered to officers in charge of the war. They are perfectly strict in casualness, and if one mark with a pen means the sacrifice of millions, it's for them just a mark of the pen. Jack Hawkings keeps up a terrible balance, constantly throwing a glance behind his back, constantly watched by the Gestapo, and ultimately no longer able to suppress his humanity. It's a great film on a small scale and definietely an enduring classic for all times.